Directory number calling line identifier



J. W. DEHN ETAL DIRECTORY NUMBER CALLING LINE IDENTIFIER 4 Sheets-Sheetl Filed May 17, 1946 .j W DEHN THQ/ DEN /N VEN TO/QS ATTORNEY ct. 1l,1949. J. w. DEHN ErAl.

DIRECTORY NUMBER CALLING LINE IDENTIFIER 4 Sheets-Sheet 2 Filed May 17,`1946 WENN /M/ENTORS @y ATTORNEY Oct. 11, 1949. Q1. w. DEHN ETALDIRECTORY NUMBER CALLING yLINE` IDENTIFIER 4 SheeS-Sheet 3 m. dbx

Filed May 17, 1946 +Mw q J. W DEH/v Nl/Mops W r HOL 05N ATTORNEY Oct.1l, 1949.

J. w. DEHN ETAL DIRECTORY NUMBER CALLING LINE IDENTIFIER 4 Sheets-Sheet4 Filed May 17, 1946 ATTORNEY Patented Oct. Il, 1949 DIRECTORY NUMBERCALLING LINE IDENTIFIER Joseph W. Dehn, Great Neck, and William H. T.

Holden, Woodside, N. Y., assignors to Bell Telephone Laboratories,Incorporated, New York, N. Y., a corporation of New York Application May17, 194e, serial No. 670,358

20 Claims.

This invention pertains to telephone systems and more particularly tosystems for identifying calling lines to determine their directorynumbers. Calling-line-identiiying devices are necessary in connectionwith the automatic recording of telephone calls and it is desirable, forthis purpose, that calling lines be identified by their directorynumbers rather than by terminal numbers, to avoid the further operationsnecessary to obtain the directory numbers for billing purposes.Identification of lines by their directory numbers presentsdiiiiculties, particularly in systems of the cross bar type where thereis no direct relation between the terminal number or physical location"of a line and its directory number. The present invention discloses aneconomical and simple system for obtaining the directory numbers ofcalling lines directly and rapidly; While particularly valuable inconnection with cross bar systems, it is not limited in its applicationto systems of that type nor to the purposes of automatic messagerecording, but is applicable to any type of telephone system and to anypurpose for which it is desirable to ascertain the directory numbers ofcalling lines.

A feature of this invention is the use of electronic devices, which areinexpensive, not subject to rapid deterioration, and readilyreplaceable.

Another feature of the invention is the use of a unidirectional pulse ofextremely short duration to effect identification, with the consequentsaving in time and equipment. The pulse may be extremely short becausethe indicating devices responsive to said pulse are affected by the rateof change of the pulse as it increases from zero to its maximum valuerather than by the specic magnitude of the pulse.

Another feature of the invention is an arrangement Iwhereby a pluralityof identiiiers may each be connected for identification of calling linesat any time without interfering with one another.

Another feature of the invention is a novel form of pulse generator foractuating identiiiers of the type disclosed.

Still another feature of the invention is the use of equipment' to servea large number of subscribers lines, not only in one central office but,if desired, in a plurality of central oflices.

These and other features of the invention will be apparent from thefollowing description, the appended claims, and the drawings, in which:

Fig. 1 shows two subscribers lines, the extension of one of said linesby switching means, and a portion of the common circuit networksprovided for identifying these and other lines;

Fig. 2 shows another portion of the common circuit networks;

Fig. 3 shows the circuit of an identiiier;

Fig. 4 shows circuits for actuating a plurality of identifiers;

Fig. 5 is a graphical representation of the potentials supplied to apulse generating tube shown in Fig. 4; and

Fig. 6 shows how the above iigures (except Fig. 5) should be placed withrelation to one another to disclose the invention.

We will first describe the arrangement of the comino-n circuit networksprovided for identification purposes, from which description the generalmode of operation of the invention will be apparent. For the purpose ofillustration, two subscribers lines II and I2 are shown in Fig. 1 and itis assumed that both of these lines are in the same central oliice,designated oiiice No. 1, and that the directory number of line II is5238, while that of line I2 is 4167.

In accordance with the present invention, the sleeve conductor of eachsubscribers line the directory number of which may be required to beidentified is connected to one element of each of two gas-discharge coldcathode tubes. For example, the sleeve conductor I3 of line II isconnected to one element of each of tubes I5 and I6, while the sleeveconductor I4 of line I2 is connected to one element of each of tubes I1and I8. The other element of each of the tubes assoi ciated with eachline is connected to one of common conductors or bus-bars,.in accordancewith the thousands and hundreds digit combination of the directorynumber of said line. For example, bus-bars THUU, THM, TH52 and THSS arefour of the 100 bus-bars provided for oflice No. 1 in which lines I Iand I2 are located, and are the bus-bars assigned to the thousands andhundreds digit combinations 00, 41, 52, and 99, respectively.Accordingly, an element of tube I5, associated with line II thedirectory number of which is 5238, is connected to bus-bar TH52, towhich are also connected corresponding elements of tubes associated withother lines (not shown) in the same central oiiice having directorynumbers the thousands digit of which is 5 and the hundreds digit ofwhich is 2. Likewise, an element of tube Il, associated with line I2 thedirectory number of which is 4167, is connected to bus-bar PTHII, towhich are also connected elements of tubes associated with other lines(not shown) in the vsame central oiiice having directory numbers thethousands digit of which is 4 and the hundreds digit of which is 1.

To each of the thousands-hundreds-digits busbars-THU!) to TH99 isconnected one element of each of three gas-discharge cold cathode diodetubes. For example, one clement of each of tubes i9, 20, and 2l isconnected to bus-bar 'FI-199, one clement o each of tubes 22, 23, and 24is connected to bus-bar TH52, one element of each of tubes 25, 26, and21 is connected to bus-bar THM, and one element of each of tubes 2B, 29and 30 is connected to bus-bar THUD. The other element of onc l thetubes connected to each thousandshundreds-digits bus-bar is connected toa bus-bar individual to the central cnice served by saidthousands-hundreds-digits bus-bar. For example, one element of each oftubes I9, 22, 25, and 28 is connected to bus-bar OFFI, which isindividual to oce No. l.

The other element of the second of the tubes associated with eachthousands-hundreds-digits bus-bar is connected to one of thousands-digitbus-bars THU to THS in accordance with the thousands digit of thethousands-hundreds-digit combination, while the other element of thethird tube associated with each thousands-hundredsdigits bus-bar isconnected to one of l0 hundreds digit bus-bars H0 to H9 in accordancewith the hundreds digit of the thousands-hundreds-digit combination. Forexample, one element of tube 23, associated with bus-bar TH52 assignedto the digit combination 52, is connected to bus-bar THS, to which arealso connected corresponding elements of tubes associated with otherthousands-hundreds-digits bus-bars (not shown) assigned to digitcombinations the rst digit of which is 5. sociated with bus-bar TH52, isconnected to busbar H2, to which are also connected correspondingelements of tubes associated with other thousands-hundreds-digitsbus-bars (not shown) assigned to digit combinations the second digit ..1

of which is 2.

The thousands-hundreds-digits bus-bars are each supplied with negativepotential, for example, from battery BI through resistances 3l, 32, 33,and 31S, and each of the ofiice, thousandsdigit and hundreds-digitbus-bars are supplied with a higher negative potential, for example,from battery B2 through resistance 35 to busbar OFFI. The difference ofpotential of batteries Bl and B2 is approximately that necessary tomaintain conduction in each tube, such as tube I9, but is insuncient toinitiate conduction in said tube. None of the gas-discharge diode tubesconnected to the bus-bars, therefore, normally conduct but will conductif the difference of potential between their elements is slightlyincreased.

It is now evident that, owing to the arrangement of bus-bars andgas-discharge tubes, if a potential is applied to the sleeve conductorof any line sufcient to cause the gas-discharge tubes connected theretoto conduct, said potential will be transmitted through said tubes tocertain of the oiice, thousands-digit and hundreds-digit bus-bars,and,upon tracing the path of said transmission, it will be apparent thatthe particular bus-bars on which said potential appears indicate a partof the directory number of said subscribers line. For example, if apotential is applied to the sleeve conductor i4 of line l2, causing tubel1 to conduct, said potential will be transmitted through the conductionofl tube l1 to bus-bar THM thence to tubes 25, 26 and 21, causing saidtubes to conduct, and through the latter tubes to bus-bars OFFl, TH4 andHl. If suitable indi- Likewise, an element of tube 24, as-

eating means are provided, the presence of Said potential on bus-barsOFFl, TH4, and Hl will indicate that line ll, to the sleeve conductor ofwhich potential was applied, is in oflce No. 1, that the thousands digitof its directory number is 4, and that the hundreds digit is l.

It is also evident that a set oi thousandshundreds-digits bus-bars THSUto THSS and an oflce bus-bar. such `as bus-bar OFFI, must be providedfor each central oice, since these busbars are used to indicate thecentral oice in which the line being identified is located, but that thethousands-digit bus-bars THD to THS and the hundreds-digit bus-bars H0to H9 may be used to serve the lines of any number of central oiiices,since these bus-bars are used only to indicate digits of directorynumbers.

A similar arrangement of bus-bars and gasdischarge tubes is used ttoindicate the tens and the units digits of directory numbers. The otherelement of the above-mentioned second gas-discharge diode tubeassociated with the sleeve conductor of each subscriber's line isconnected to one of 100 tens-units-digits bus-bars, of which bus-barsTUBO, TU38, TUM and TU99 are four, in accordance with thetens-units-digits combination of the directory number of said line. Forexample, an element of tube I6 associated with line Il the directorynumber of which is 5238, is connected over conductor 36 to bus-bar TU38,to which are also connected corresponding elements of tubes (not shown)associated with other lines the directory numbers of which coinprise thetens-units digit combination 38, while an element of tube I8, associatedwith line l2 the directory number of which is 4167, is connected overconductor 31 to bus--bar TU61, to which are also connected correspondingelements of tubes (not shown) associated with other lines the directorynumbers of which comprise the tens-units digit combination 67.

To each of the tens-units-digits bus-bars TUBO TUBE is connected oneelement of each of two gas-discharge cold cathode diode tubes. Forexample, one element of each of tubes 38 and 39 is connected to bus-barTUSS, one element of each of tubes 4U and 4| is connected to bus-barTUGl, one element of each of tubes 42 and 43 is connected to bus-barTU38, and one element of each of tubes 44 and 45 is connected to bus-barTUUO. The other element of one of the tubes associated with eachtens-units-digits bus-bar TUBO TUSS is connected to one of l0 tens-digitbusbars T0 T9 in accordance with the tens digit of the tens-units-digitscombination, and the other clement of the second tube associated witheach tens-units-digits bus-bar is connected to one of l0 units-digitbus-bars U0 U9 in accordance with the units digit of said combination.For example, an element of tube 40 associated with bus-bar TUBT,assigned to the digit combination 67, is connected to bus-bar T6, towhich are also connected corresponding elements of tubes (not shown)associated with other tensunits-digits bus-bars assigned to digitcombinations the tens digits of which is 6, and an element of tube 4l,also associated with bus-bar TUST, is connected to units bus-bar U1, towhich are also connected corresponding elements of tubes (not shown)lassociated with other tensunits-digits bus-bars assigned to digitcombinations the units digit of which is 7. Each bus-bar is suppliedwith suitable potential, the tens-unitsdigits bus-bars NUOD TUSS withnegative potential from battery B3 through resistances,

such 'as resistance 48, and the tens-digit and units-digit bus-bars T T9and U0 U9, respectively, with higher negative potential from battery B4,through resistances such as resistance 41, such-that the gas-dischargediode tubes connected to said bus-bars do not normally conduct but willconduct if :the potential dilerence between their elements is slightlyincreased.

It is evident that if a potential is applied to the sleeve conductor ofany line suilicient to cause the gas-discharge tubes connected theretoto con duct, said potential will be transmitted through said tubes tocertain of the tens-digit and unitsdigit bus-bars and the presence ofpotential on those bus-bars will indicate the tens and units digits ofthe directory number of said line. For example, if potential is appliedto sleeve conductor I4 of line I2, causing tube I8 to conduct, saidpotential will be transmitted through said tube, over conductor 31 tobus-bar TUBI, thence to tubes 48 and 4I, causing said tubes to conduct,and through said tubes to bus-bars T6 and U1, indicating that the tensand units digits of the directory number of line I2 are 6 and 7,respectively.

It is also evident that the tens-units-digits busbars TUll TU99, thetens-digit bus-bars T0 T9, and the units-digit bus-bars U0 U9 may beused to serve any number of lines located in any number of central oicessince they are employed to indicate digits of directory numbers of linesirrespective of the central offices in which said lines are located.

By the use of additional bus-bars and additional gas-discharge tubesconnected in the manner described, the system may be extended to providemeans for indicating directory numbers of more than four digits or otherinformation in regard to a line identified, such as the class of theline or its rate zone.

For utilizing the means provided by the common circuit networks for theldentication of calling' lines, an identifier circuit (shown in Fig. 3)is employed which comprises an indicating tube and an associatedregistering tube connected through a condenser, to each of the oiice,thousands-digit, hundreds-digit, tens-digit, and units-digit busbars, apulsing tube, and registers for the office number and for each of thefour digits of the directory number. For example, tube 48 is anindicating tube and tube 49 a registering tube associated withthousands-digit bus-bar TH5; tube 50 is an indicating tube and tube 5I aregistering tube associated with hundreds-digit busbar H2; tube 52 is anindicating tube and tube 53 a registering tube associated withtens-digit busbar T3, while tube 54 is an indicating tube and tube 55 aregistering tube associated with units-l digit bus-bar U8. Tube 56 isthe pulsing tube of the identifier comprising the above-mentionedindicating and registering tubes and the other indicating andregistering tubes associated with each of the digital bus-bars THU THS;H0...H9;T0...T9andU0...U9. Inthe present embodiment of the invention,the indicating tubes and the registering tubes are gasdischarge 'triodetubes of the cold cathode type and the pulsing tube is a gas-dischargetetrode tube of the heated cathode type. The registers may be of anysuitable type and may each be similar to the register for the unitsdigits, comprising relays R0, R8, R9, CK, and ON, disclosed in Fig. 3.

The control anode of each of the indicating tubes, for example, tube 54,is supplied with positive potential by positive battery throughresistances,51 and 58 and this potential is of such value that said tubewill not normally conduct even when its main anode is also supplied withpositive potential, but will conduct if, at the same time, the potentialof its control anode is slightly raised. The main anodes of all theindicating tubes of Aan identiiier, such as tubes 48, 50, 52 and 54, areconnected to the cathode of the associated pulsing tube, in this case,tube 56. The anode of the pulsing tube 56 is supplied with alternatingpo tential from the source 59 through transformer 60. The control gridof said tube is biased by negative battery through resistance 6I so thatsaid tube doe's not normally conduct, but will conduct if the potentialof its control grid is made slightly less negative. The main anode ofeach of the registering tubes, for example, tube 55, is

supplied with positive potential and the control anode biased bypotential from the voltage divider composed of resistances 62 and 63, sothat said tube does not normally conduct but will conduct if its controlanode is made slightly more positive. Y

To identify a calling line, for example, line II extended by line link64, district link 65, and oiice link 66, the cathode of the pulsing tubeof an identier, for example, tube 56, of the identier shown in Fig. 3,is connected through resistance 61 and conductor 68 to sleeve conductorI3 of said line, as extended, at any convenient point in the partiallyestablished connection by suitable means, such as relay SI or relay S2.The control grid of tube 56 is then made, by suitable means such as thathereinafter described, momentarily suiciently less negative to causesaid tube to conduct during the positive half of one cycle ofalternating current.

The sleeve conductor of a subscribers line, for

example, conductor I3, is used in automatic telephone systems for otherpurposes, chief among which is the holding of the magnets of the variousswitches by which the line is extended. Rectifier 69 provides a path toground for the negative potential by which said magnets are held butopposes the passage of positive potential. The positive pulse from thecathode of tube 56 will not,` therefore, pass through rectifier 69 butwill be transmitted over conductor 63 through contacts of relay SI orrelay S2 to sleeve conductor I3 as extended and to tubes I5 and I6,causing said tubes to conduct, thence by the conduction of tube I5, tobus-bar TH52 and by the conduction of tube I6, to bus-bar TU38. Thepulse of positive potential on bus-bar TH52 will cause tubes 22, 23, and24 to conduct and, by the conduction of tube 22, will be transmitted tobus-bar OFFI, by the conduction of tube 23, to bus-bar TH5, and by theconduction of tube 24, to bus-bar H2. Likewise, the positive pulse onbus-bar TU38 will cause tubes 42 and 43 to conduct. By the conduction oftube 42, said positive pulse will be transmitted to bus-bar T3 and, bythe conduction of tube 43, to bus-bar U8.

The positive pulse on bus-bar U8 will be transmitted over conductor 'I0and will produce, through condenser 1I a pulse, the magnitude of whichwill depend upon the rate of change in potential of the pulse applied tosaid condenser. The pulse from condenser 1I will be transmitted throughresistance 51 to the control anode of tube 54, causing said tube toconduct momentarily since, at the same time, a pulse of positivepotential is received on the main anode of said tube from the cathode oftube 56. The rise of potential at the cathode of tube 54, due to theconduction of said tube, will be transmitted through condenser 12 to thecontrol anode of tube 55, causing tube 55 to conduct over a circuitextending from positive battery, through the anode-cathode space of tube55, resistance 13, No. 1 normal contact of relay R8, and the winding ofsaid relay to negative battery.

In like manner, the positive pulse on bus-bars OFFI, THS, H2, and T3will cause conduction 55,-may be registered by means of a relay circuitsuch as that shown in Fig. 3 for registering the units-digit indication.Only three register relays R0, R8 and R8 are shown, but it will beunderstood that the circuit comprises 10 such relays, each connected toa corresponding register tube in the manner shown for relay R8 and tube55.

The current which normally flows from positive battery throughresistances 62, 53 and 13, No. l normal contacts of relay R8, and thewinding of said relay to negative battery is not sufficient to operaterelay R8. When tube 55 conducts, however, as described above, thedecreazcd resistance in the circuit causes additional current to ow,operating relay R8 which locks up through its own No. 1 front contactand No. 2 contacts of normally-operated relay ON. The operation of relayR8 opens at the No. 1 normal contact, the circuit of tube 55, causingsaid tube to cease to conduct and, at the No. 3 back contact of saidrelay, opens'the normal operating circuit of relay ON, which extendsfrom batter through the winding of relay ON, and No. 3 back contacts ofrelays R to R9 inclusive, (relays R8, R8, and R9 only being shown) toground. However, relay CK now operates over a circuit extending frombattery through the winding of said relay, No. 2 contacts of relays RDto R1 (relay RD only being shown), No. 3 front contact of relay R8 andNo. 3 back Contact of relay R8 to ground, providing an obviousadditional circuit through its contacts for relay ON which preventsrelease of relay ON.

If, through some fault in the circuits, more than one of the registerrelays R0 lto R9 are operated at the same time, the circuit of relay CKwill not be completed. Relay CK will, therefore, not operate and relayON will release. A circuit will then be completed from ground throughback contact of relay CK and No. l contacts of relay ON to an alarm (notshown) actuating said alarm.

A plurality of identifiers of the type described may be associated withthe same bus-bars in the manner described for the identifier comprisingthe tubes shown in Fig. 3. If the respective pulsing tubes 56 of theseidentifiers are actuated repeatedly and in succession, no two pulsingtubes being actuated at the same moment, then any or all of saididentifiers may be connected to calling lines for identification at thesame time and each identifier will identify the line to which it isconnected. For example, assume two identiers to be associated withbus-bars U0 to U9. Then to each of bus-bars U0 to U9 will be connectedtwo indicating tubes similar to tube 54 and in the manner shown for tube54. The main anode of one of said tubes associated with each bus-barwill be connected to the cathode of a pulsing tube, similar to tube 56,of a first identifier, while the main anode of the other of said tubesassociated with each bus-bar will be connected to the cathode of apulsing tube, similar to tube 59, associated with the second identifier.1f the cathode of said first pulsing tube be connected to the extendedsleeve conductor of a line having a directory number the units digit ofwhich is 6 and the cathode of said` second pulsing tube be connected tothe extended sleeve conductor of a line having a directory number theunits digit of which is '1, and the two pulsing tubes be energized insuccession, a positive pulse will appear on bus-bar U6 when said firstpulsing tube is energized and will reach both indicating tubes connectedto said bus-bar, while a positive pulse will appear on bus-bar U1 whensaid second pulsing tube is energized and will reach both indicatingtubes connected to bus-bar U1. But the firstmentioned positive pulsewill affect only the iirst of the two indicating tubes connected tobus-bar U6, since the main anode of said tube is, at the moment,supplied with potential from the cathode of said iirst pulsing tube,while the main anode of the second indicating tube is not supplied withpotential. Likewise, the second-mentioned positive pulse will affectonly the second of the two indicating tubes connected to bus-bar U1,since the main anode of said tube is, at the m0- ment, supplied withpotential from the cathode of said second pulsing tube, while the mainanode of the first indicating tube is not supplied with potential, Inlike manner, other indicating tubes, and consequently the associatedregistering tubes, are aiected by pulses produced by the associatedpulsing tube but are unaffected by pulses produced by the pulsing tubesof othe:- identifiers.

A circuit arrangement for actuating identifiers in rapid succession forthe purpose described above is shown in Fig. 4. It includes a pulsegenerating tube 14 and a circuit of the type known as a thyratron ring,comprising tubes 15, 18, 11, and 18. This circuit is arranged foractuating four identiiiers but, by extention of the thyrairon ring, maybe adapted to the actuation of any number of identifiers.

One winding of transformer is supplied with alternatlng current overconductors 8| and 82 through transformer 60 from the same source 59which supplies anode potential to tube 56 and to pulsing tubes (notshown) of three other identifiers to be actuated. Alternating potentialfrom the other winding of transformer 80 is biased by negative potentialfrom the voltage divider composed of resistances 83 and 84 and suppliedto the network composed of resistance 85 and condenser 86, the values ofwhich are so chosen that the potentials at rectifiers 81 and 88 have aphase difference of nearly but not exactly degrees. Curves A and B inFig. 5 show graphically the relative potentials applied to rectifiers 81and 88, respectively. Said rectifiers are poled so that they opposetransmission of positive potentials. |I'he resultant potentialtransmitted through rectifiers 81 and 88 and thence through resistance89 to the control grid of tube 14, which, in the present embodiment ofthe invention is a gas-discharge triode tube of the heated cathode type,is shown by the heavy line curve of Fig. 5. It will be observed thatsaid control grid is maintained sumciently negative l to preventconduction in tube 14, except during a short period in each cycle whenits potential approaches zero suiiiciently to permit tube 14 to conduct.The anode of tube 14 is supplied with voperating potential through theself-clearing anode circuit comprising resistance 90 and condenser 9|,the values of which are so chosen in relation to the valueof the anodepotential and the characteristics of tube 14 that the discharge ofcondenser 9|, due to the drop of potential through resistance 90 whentube 14 conducts, maintains conduction until the control grid of tube 14again goes negative, when the potential between the main anode and thecathode of said tube is insufficient, due to the potential drop inresistance 90, to maintain conduction.

Tube 14, therefore, conducts for a very short period in each cycle ofalternating current, producing, at its cathode, short positive pulseswhich are transmitted through resistance 92, thence through condensers93, 94, 95, and 96 and resistances 91, 98, 99 and |00 to the controlanodes of the gas-discharge cold cathode triode tubes 15, 16, 11 and 18.The control anodes of said tubes are each negatively biased. Forexample, the control anode of tube 16 is biased by negative batterythrough resistances |02, and 91. The amplitude of the pulses from thecathode of tube 14 is limited by rectier |03 to a value insufficient initself to overcome said negative bias and cause tubes 15, 16, 11, and 18to conduct. Upon the closure of switch |04 to apply anode potential totubes 15, 16, 11 and 18 the sudden rise of potential at the main anodeof tube 15 is transmitted through condenser to the control anode of saidtube, said rise of potential in addition to a positive pulse received atsaid control anode from the cathode of tube 14 being suflicient to causetube 15 to conduct. A part of the resultant rise of potential at thecathode of tube 15, the amount being determined by the voltage dividercomposed of resistances |0| and ||0 is, however, transmitted through thenetwork composed of resistances |02 and 91 and condenser with a timedelay due to the characteristics of said network, to the control anodeof tube 16, raising the potential of said control anode so that theadditional potential of the next positive pulse from the cathode of tube14 is sufiicientto cause tube 16 to conduct. The resultant sudden riseof potential at the cathode of tube 16 is transmitted through condenser|06 to the cathode of tube 15` raising the potential of said cathode toa point where tube 15 ceases to conduct. A part of said rise ofpotential at the cathode of tube 16, the amount being determined by thevoltage divider composed of resistances ||2 and H3, is transmittedthrough the network composed of resistances ||4 and 98 and condenser ||5with a time delay due to the characteristics of said network to thecontrol anode of tube 11 so that, upon receipt of the next positivepulse from the cathode of tube 14, tube 11 conducts, causing conductionin tube 16 to cease and preparing tube 18 for conduction on the nextpulse from tube 14 in the manner described for tube 16.

This action is repeated, tubes 1B, 157 16, 11, 18, conducting insuccession indenitely.

.Each time tube 18 conducts, a positive pulse is produced at the cathodeof said tube which is transmitted over conductor |6 to the control gridof pulsing tube 56 individual to the identiiier shown in Fig. 3,actuating said tube in the manner previously described, and each timetubes 15,

16 and 11 conduct, positive pulses are produced at the cathodes of saidtubes which are transmitted over conductors ||1, H8 and ||9,respectively to the pulsing tubes (not shown) of three otheridentifiers. The cathode of tube 56 and similar pulsing tubes of saidother identifiers, need only be connected to the extended sleeveconductors of lines, as previously described, during a period sufcientfor each ofsaid tubes to receive one pulse to identify each of saidlines.

A large number of lines are dependent for identiiication upon thepotentials supplied to the busbars for actuating the gas-discharge diodetubes associated with them. Therefore, each bus-bar should be providedwith an alarm circuit to give immediate warning of the failure of any ofsaid potentials. Suitable alarm circuits are disclosed in Fig. 2. Eachof the thousands-hundredsdigits bus-bars and each of thetens-units-digits bus-bars may be provided with an alarm circuit similarto that shown, as an example, associated with bus-bar TU61. The mainanode of tube |20 which, in the present embodiment of the invention is agas-discharge triode tube of the cold cathode type, is supplied withalternating potential from the source |2| through the winding of relayAI, while the cathode of said tube is supplied with positive potentialdirectly applied thereto. The diierence of potential between the anodeand the cathode of tube |20 is at no time sufiicient to initiateconduction in said tube but is suicient to maintain conduction onnegative cycles of alternating current. Negative potential appliedthrough resistance 46 to bus-bar TU61, thence through resistances |22and |23 to the control anode of tube |20 causes said tube to conduct onnegative cycles of alternating current, operating relay AI. Thedischarge of condenser |24 through resistance 22 maintains the controlanode of tube |20 sufiiciently negative when positive pulses arereceived on bus-bar TU61 so that tube 20 does not cease to conductduring the period of said pulses. If, however, the negative potentialthrough resistance 46 should fail, tube |20 will cease to conduct,releasing relay AI, which completes a circuit to an alarm (not shown)actuating said alarm.

Each of the oiilce, thousands-digit, hundredsdigit, tens-digit, andunits-digit bus-bars may be provided with an alarm circuit similar tothat shown, as an example, associated with bus-bar U0. Tube |25, whichin the present embodiment of the invention is a gas-discharge triodetube of the cold cathode type, is supplied with anode potential in amanner similar to tube |20, its cathode being connected to ground.Negative potential through resistance 41 to bus-bar U0, thence throughresistance |21 to the control anode of tube |25 causes said tube toconduct on negative cycles of alternating current, operating relay A2.Positive pulses received on bus-bar U0 are insuiiicient to overcome thehigh potential supplied by battery B4 to the control anode of tube |25.However, should the potential through resistance 41 fail, tube |25 willcease to conduct, releasing relay A2 which completes the circuit of analarm (not shown) actuating said alarm.

All of the tubes shown in the present embodiment of the invention are ofthe gas-discharge type. However, it will be apparent to one skilled inthe electronic art that other forms of tubes such as vacuum tubes orother discharge devices could readily be substituted to perform thefunctions of the tubes described.

What is claimed is:

1. In a signaling system, a line having an identifying designation,conductors indicative of said designation, means for applying aunidirectional impulse to said line, means for directing said impulse tosaid conductors, and means for utilizing the change in the magnitude ofsaid impulse on each of said conductors to register the designation ofsaid line.

2. In a signaling system, a line having an identifying designation,conductors indicative of said designation, means for applying aunidirectional pulse of electric energy to said line, gasdischargedevices responsive to said pulse to direct said energy to saidconductors, and gas-discharge devices responsive to the variation in thepotential of said energy on each of said conductors.

3. In a signaling system, a line having an identifying designationcomposed of digits, a gas-discharge pulse generator, means for applyinga pulse from said pulse generator to said line, gas-discharge devicesresponsive to said pulse to transmit said pulse over paths indicative ofthe digits of said designation, other gas-discharge devices responsiveto said pulse on each of said paths for indicating the digits of saiddesignation, and means for registering each of said indications, Y

4. In a signaling system, a line having an identifying designationcomposed of digits, a gas-discharge pulse generator, means for applyinga pulse from said generator to said line, a rst group of gas-dischargedevices associated with said line for directing said pulse over paths inaecordance With combinations of the digits of said designation, a secondgroup of gas-discharge devices associated With said paths for directingsaid pulse over other paths in accordance with the individual digits ofsaid combinations of digits, and a third group of gas-discharge devicesresponsive to said pulse on each of said other paths.

5. In a system for identifying telephone lines, the combination withlines each having an identifying designation, of conductors indicativeof said designations, means for applying a unidirectional pulse to anyone of said lines, means associated with said line for directing saidpulse over said conductors in accordance with the designation of saidline, and means responsive to the variation in magnitude of said pulseand common to all of said lines for registering said pulse on each ofsaid conductors.

6. In a system for identifying telephone lines, the combination withlines each having an identifying designation, of means for applying apulse to any one of said lines, means comprising gasdischarge devicesfor directing said pulse over paths indicative of the designation ofsaid line, and means comprising gas-discharge devices for receiving andregistering said pulse on each of said paths` '7. In a system foridentifying telephone lines, the combination with lines each having anidentifying designation, of a pulse generator comprising gas-dischargedevices, means for applying a pulse from said generator to any one ofsaid lines, a rst group of gas-discharge devices associated with saidline for directing said pulse over paths indicative of the designationof said line, a second group of gas-discharge devices common to all ofsaid lines for directing said pulse over other paths indicative of thedesignation of said line, and a third group of gas-discharge devicescomtaneously to one of said lines and to all of said receiving devices,means for directing said pulse from said line to said receiving devicesin accordance with the designation of said line. and means responsive tothe change in magnitude of the pulse applied to said line forregistering the coincidence at each of said receiving devices of thepulse applied to said receiving device and the pulse directed to saidreceiving device from said line.

9. In a system for identifying telephone lines, lines each having anidentifying designation composed of digits, a plurality of gas-dischargereceiving devices, means for applying a pulse simultaneously to any oneof said lines and to all of said receiving devices, gas-dischargedevices associated with each of said lines for transmitting said pulse,gas-discharge devices common to all of said lines for transmitting saidpulse to said receiving devices in accordance with the designation ofthe line to which said pulse is applied, and means for registering thecoincidence at each of said receiving devices of the pulse applied tosaid receiving device and the pulse transmitted to said receiving devicefrom said line.

10. In combination, a plurality of lines each having an identifyingdesignation, means for applying a unidirectional pulse to each of saidlines in succession, a plurality of groups of receiving devices eachresponsive to the variation in the magnitude of one of said pulses, andmeans for directing each of said pulses to said receiving devices toindicate the designation of the line to which said pulse is applied.

11. In a system for identifying telephone lines, in combination withlines having identifying designations, a plurality of identifyingcircuits each responsive to the variation in the magnitude of aunidirectional impulse of short duration, means for generating suchimpulses, means for connecting each of said identifying circuits to oneof said lines, and means for applying an impulse successively to each ofsaid identifying circuits to indicate the designations of said lines.

l2. In a system for identifying telephone lines, in combination withlines having identifying designations, gas-discharge devices associatedwith each line for identifying said line, gas-discharge devices commonto all of said lines for identifying any of said lines, a plurality ofidentifying circuits each capable of being made responsive to impulsestransmitted through said gas-discharge devices from any one of saidlines, means for successively making responsive each of said identifyingcircuits and simultaneously applying impulses to said lines, and meansfor registering the response of each of said identifying circuits.

13. In a signaling system, individual conductors having arbitrarydesignations, common conductors, and means for directing and varying themagnitude of a unidirectional impulse applied to one of said individualconductors selectively to said common conductors to identify thearbitrary designation of said individual conductor.

14. In a signaling system, individual conductors having arbitrarydesignations, common conductors, and electronic devices for directingand varying the magnitude of a unidirectional impulse applied to one ofsaid individual conductors selectively to said common conductors toidentify the arbitrary designation of said individual conductor.

15. In a signaling system, individual conductors having arbitrarydesignations, and common conductors each having an indicating deviceresponsive to the variation in the magnitude of a unidirectional imnulseapplied to one of said individual conductors and selectably directed tosaid common conductors to identify the arbitrary designations of saidindividual conductor by the operation of the indicating devices of thecommon conductors to which said impulse is directed.

16. In a signaling system, individual conductors having arbitrarydesignations, common conductors. electronic devices for selectablydirecting a unidirectional impulse applied to one of said individualconductors to said common conductors in accordance with the arbitrarydesignation oi' said individual conductor, and electronic devicesresponsive to the variation in the magnitude oi' said impulse toindicate said designation.

17. In a system for identification of telephone lines, lines havingnumerical designations, common conductors corresponding to digits ofsaid designations. electronic devices selectablv connecting said linesto said common conductors, electronic devices interconnecting saidcommon conductors. and means for applying a unidirectional irnpulse ofvarving magnitude to one of said lines to indicate the designation ofsaid line.

18. In a system for the identification of telephone lines, a pluralityof groups of lines, a common conductor corresponding to each of saidgrouns. electronic devices seiectably connecting said lines to saidcommon conductors, and means for applying a unidirectional impulse ofvarying magnitude to one of said lines to indicate the groun of whichsaid line is a part.

19. In a svstem for identifying telephone lines, lines having numericaldesignations. a rst group of common conductors for combinations ofthousands and hundreds digits of said designations, a second group ofcommon conductors for combinations of tens and units digits of saiddesignations. electronic devices connecting said lines to said firstgroup of common conductors in accordance with the thousands and hundredsdigits of their respective designations. electronic devices connectingsaid lines to said second group of common conductors in accordance withthe tens and units digits of their respective designations, a thirdgroup of common conductors for thousands digital values of saiddesignations. a fourth group of common conductors for hundreds digitalvalues of said designations, electronic devices connecting said firstgroup of common conductors to said third and fourth groups of commonconductors in accordance with -the thousands and hundreds digitsrespectively of said designations, a fifth group of common conductorsfor tens digital values of said designations, a sixth group of commonconductors for units digital values of said designations, electronicdevices connecting said second group of common conductors to said fthand sixth groups of common conductors in accordance with the tens andunits digits respectively of said designations, and means for applyingpotential to one of said lines whereby certain of said electronicdevices are operated to indicate the designation of said line.

20. In a system for identifying telephone lines, a plurality of groupsof lines having numerical designations, a first common conductor foreach combination of thousands and hundreds digits of said designationsin each of said groups, electronic devices connecting each of said linesto one of said iirst common conductors in accordance with the thousandsand hundreds digits of the designation of said line and the group inwhich said line is located, a second common conductor for each of saidline groups, a third common conductor for each thousands digital valueof said designations, a fourth common conductor for each hundredsdigital value of said designations, electronic devices connecting eachof said rst common conductors to one of said second common conductors,one of said third common conductors and one of said fourth commonconductors in accordance with the line group, the thousands digit, andthe hundreds digit of said designations, respectively, a fifth commonconductor for each combination of tens and units digits of saiddesignations, electronic devices connecting each of said lines to one ofsaid fifth common conductors in accordance .with the tens and unitsdigits of the designation of said line, a. sixth common conductor foreach tens digital value of said designations, a seventh common conductorfor each units digital value of said designations,` electronic devicesconnecting each of said fifth common conductors to one of said sixthcommon conductors and one of said seventh common conductors inaccordance with the tens digit and the units digit of said designations,respectively, and means for applying potential to one of said lineswhereby certain of said electronic devices are operated to indicate thedesignation of said line.

JOSEPH W. DEHN. WILLIAM H. T. HOLDEN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,663,747 Bascom Mar. 27, 19281,690,206 Raynsford Nov. 6, 1928 1,841,084 Bragg Jan. 12, 1932 2,005,595Roome June 18, 1935 2,084,105 Myers June 15, 1937 2,153,179 Fitch Apr.4, 1939 2,226,459 Bingley Dec. 24, 1940 2,267,950 Rhodes Dec. 30, 19412,319,424 Maloney May 18, 1943

